来自农村的老师可能都有在土灶上煮饭的经验:一大锅的饭,你要煮得好吃、香喷喷的,火候的掌握非常重要——先旺火而后再小火,这样的饭才香;如果你第一次没煮好、煮熟,无论第二次你怎么加工永远也成不了一锅好饭。这使我想到我们的课堂教学也有类似的情况:教师预设某项知识要在某 Teachers from rural areas may have experience in cooking on the soil stove: a big pot of rice, you want to cook delicious, fragrant, the heat of the master is very important - the first fire and then a small fire, such a meal It is fragrant; if you do not cook for the first time, cooked, no matter how you process for the second time can never become a pot of good rice. This reminds me of our classroom teaching has a similar situation: the teacher prescribes a certain knowledge to be in a